Music library keeps disappearing on macOS Tahoe 26.0.1 after import

I recently replace my Mac Mini with a new model and installed Tahoe. I copied my music files ( over 3Tb!) to the new machine and it's external HDD. I then imported the playlist ticking Keep media folder organised and Copy files to Media folder when adding to Library. It took nearly 20 hrs but the libary was imported and I was able to play songs. I closed down Music and it threw an error. The Library was empty when I next opened music. and the Library

Each time I have done imported the playlist and close down Music it throws an error and the Library is lost with only a couple of songs I purchased from Apple visible. The song files are in the folder but they are not in the Library. I have done this several times and was hoping Tachoe 26.0.1 would fix the issue.

The error is:

Any ideas anyone?

[Edited by Moderator]

Original Title: Music on Tahoe